1. Field of the Invention
The present invention relates to electronic musical instruments, and more particularly to electronic synthesizers, in which a signal of desired amplitude and wave shape is produced under the control of a variety of manual controls. Such a signal must be produced either repetitively or when triggered by a control signal.
2. The Prior Art
In known designs for synthesizer instruments, the wave shape produced by the sound source is typically either a sine wave or a square wave. Both of these wave shapes are relatively easy to generate, and they may be transformed from one to the other without difficulty. Other wave shapes may be derived from them, with the result that a variety of wave shapes may be obtained simply by manipulation of sign and square waves.
Although such fundamental wave shapes can be used with great success, it is desirable to provide apparatus for making a greater variety of wave shapes available, with the use of a limited number of controls which may be adjusted by the operator or player of the instrument. In particular, it is desirable to have one control for varying the wave shape of a signal produced by the apparatus, without any effect on the frequency of the signal, and another control for varying the frequency of the signal without having any effect on its wave shape.